Problem: When I view my GooglebaseXML feed it shows the error:
XML Parsing Error: XML or text declaration not at start of entity
Line Number 2, Column 1:<?xml version="1.0" encoding="UTF-8" ?>
Solution: The error in your XML feed is usually caused by a plugin inserting an empty space at the start of the XML document. Unfortunately the specification for an XML document is very precise and this is not allowed: the <xml> tag must be the very first thing in the document.
If you go to your site index.php page and look at the page source you will probably see that there is also an empty space or line inserted at the start of the html document, by the same plugin, strictly this makes the html invalid but web browsers just deal with this sort of thing.
The way to solve this is to try temporarily disabling each of your active plugins in turn, and seeing if the error goes away. The problem is not caused by any of the Joomla core plugins, it will be a third party one that is responsible. Also it seems to be only system plugins that cause this problem, so you can narrow your search to 3rd party system plugins. Occasionally it can be a problem with your site index.php file if this has been edited, but this is more rare.
Once you have the offending culprit you are welcome to send it to us and we will help remove the problem, it is usually just an empty space outside <?php> tags that cause the problem so it is easy to fix.